Lifting arm



FIG. 1 is a left-side, back perspective view of a lifting arm;

FIG. 2 is a left side view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a back view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a right-side, front perspective view thereof;

FIG. 9 is a first front perspective view of the lifting arm, shown in an environment of use; and,

FIG. 10 is a second front perspective view of the lifting arm, shown in an environment of use.

The broken lines in the drawings are for the purpose of illustrating both environment and portions of the lifting arm that form no part of the claimed design. 

CLAIM We claim the ornamental design for a lifting arm, as shown and described. 